Theodore berdell



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TELEPHONE.

I Patented Nov. 23, 1897.

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w/ mssszs UNITED Snares Parnwr @rnrcn THEODORE BERDELL, OF NEW YORK, N. Y.

TELEPHQNE.

SPECIFICATION forming part of Letters Patent No. 594,060, dated November 23, 1897 Application filed December 27, 1895. Serial No. 573,433. (No model.)

To aZZ whom it may concern:

Be it known that I, THEODORE BERDELL, a citizen of the United States, residing in the city, county, and State of New York, have invented new and useful Improvements in Telephones, of which the following is a specification.

My invention relates especially to tele phone-transmitters, and has for its object the provision of an instrument which is practically self-adjusting, simple in construction, and very effective in operation.

To attain the desired end my invention consists, essentially, in two flexible diaphragms rigidly held at their peripheries and free and unencumbered at their centers and having granular material or spheres or balls held therebetweenaround the central unoccupied space; and my invention also involves certain other novel and useful combinations or arrangements of parts and peculiarities of construction, all of which will be hereinafter first fully described, and then pointed out in the claims.

I11 the accompanying drawings, forming a part hereof, Figures 1 and 2 are axial sectional views of transmitting-telephones embodying my invention. Fig. 3 is a like view of a receiving-telephone, showing my transmitter as combined therewith.

Like numerals of reference, wherever they occur, indicate corresponding parts in all the figures.

1 is a back piece of insulating material.

2 is a front or mouth piece of like material engaging with the back piece 1 by a screwthread or held thereto in any other desirable manner.

3 is the rear diaphragm, fitting snugly in place upon a ledge 4: and carrying a ring 5. This ring may be secured to the diaphragm by screws, cement, or in any other equivalent manner, or where used as illustrated in Figs. 1 and 3 it may be formed with the diaphragm and of any material, conducting or otherwise; but when used as in Fig. 2 said ring must be of non-conducting material, for reasons that will be hereinafter explained.

6 is the front diaphragm, held in place between the back piece 1 and mouthpiece 2.

7 is the electrical connection to the diaphragm 3, and S the connection to the diaphragm (3.

0 are balls of conducting materialsuch, for instance, as carbonloosely placed between the two diaphragms 3 and G and held near the peripheries of the diaphragms by the central ring,5. VJhere electrodes of this character and general shape and size are used, the ring 5 need be only of sufiicient height to prevent the balls from falling out of place, and such ring may be of any material; but where granular material 10, such as illustrated in Fig. 2, is used instead of the balls the ring 5 must be of insulating material, and the outer diaphragm must come in con tact therewith to prevent the granules from escaping from the annular chamber wherein they are inclosed.

In applying my transmitter to a receiving instrument the center of the diaphragm 3 may be cut away and the parts arranged as shown in Fig. 3.

By long and careful experiment I have found that the best effects in transmitting tones, particularly of articulate speech, are obtained by placing the contactelectrodes near the peripheries of the diaphragms instead of substantially at the center, as has heretofore been the practice, and by the arrangement illustrated in the drawings my invention is practically carried into effect. This improved result apparently depends upon the fact that as the central portion of each diaphragm within the ring 5 is unencumbered and a free unoccupied space is left between the diaphragms for some distance about their centers an unimpeded movement and greater amplitude of vibration of that diaphragm upon which the sound-waves impinge are provided for, and the compression of the annularly-arranged granules or balls is greater than in those constructions in which the movement of the central portion of said dia phragm is impeded, as in some instances, by a block of carbon bolted thereto or granular carbon interposed between it and a rear support. Then, too, the rear support in my device being a flexible diaphragm a modulated compression and expansion of the granules or balls are provided for, thereby causing the instrument to respond more freely and accurately to vocal sounds.

Having now fully described my invention, what I claim as new therein, and desire to secure by Letters Patent, is

1. In a telephone, two adjacent flexible diaphragms secured in place at their peripheries and unencumbered at the center portions of their facing sides thereby leaving a free space between them at that place, and granular or spherical material confined between the diaphragms about the central space, for the purpose set forth.

2. A telephone in which are comprised two diaphragms unencumbered at their centers and held apart at their peripheries in an insulating-case, a ring of insulating material held between the diaphragms, and spherical or granular material loosely held in the space outside of the ring, the space between the diaphragms Within the ring being unoccupied, substantially as shown and described.

3. In a telephone, two adjacent flexible diaphragms secured in place at their peripheries and unencumbered at the center portions of their facing; sides thereby leaving; a free space between them at that place, granular or spherical material confined between the diaphragms about the central space, and an electromagnet arranged to act upon one of said diaphragms for the purpose set forth.

4-. In a telephone two adjacent flexible dia' phragms one of which is cut away at its center, a magnet extending into the opening so formed in the one diapl'iragm and arranged to act upon the other diaphragm, and granular or spherical material confined between the diaphragn'ls around said opening for the pn rpose set forth.

THEODORE BER'DELL;

Witnesses:

A. M. PIERCE, BEATRICE M. DONAL'DSON. 

